An organic light emitting device (OLED) is typically formed of two electrodes (an anode and a cathode), and one or more organic material layers placed between these electrodes. In the organic light emitting device having such a structure, when voltage is applied between the two electrodes, holes from the anode and electrons from the cathode flow into the organic material layer. The holes and the electrons are bonded to form excitons. The excitons fall back to the ground state and emit photons that correspond to the energy difference. By this principle, the organic light emitting device generates visible light. An information display device or an illumination device can be manufactured using the organic light emitting device.
Technologies to increase the efficiency of the organic light emitting device and lower the driving voltage have been continuously developed in order to widen the scope of application of the organic light emitting device and commercialize the organic light emitting device.